RU2607626C2 - Method of propylene production by recycling of heavy fractions - Google Patents

Abstract

FIELD: manufacturing technology.

SUBSTANCE: invention relates to two versions of method of propylene production. One of versions includes: metathesis reaction of raw supply stream consisting of mixture of n-butene with ethylene in presence of metathesis catalyst to form fraction containing propylene, ethylene, butene and C₅₊ olefins, 2-pentene and 3-hexene; extraction of propylene from ethylene, butene and C₅₊ olefins from fraction of metathesis products; and recirculation of at least part of C₅₊ olefins for metathesis reaction recycled C₅₊ olefins are converted into propylene and butene, wherein ethylene is introduced into metathesis reaction at ratio, which is sufficient for maintaining reaction, where C₄₊ ratio for reaction with metathesis catalyst ranges from 0.3:1 to 3:1 and at least 5 % of C₅₊ olefins return into metathesis reaction.

EFFECT: use of recycling of C₅₊ olefin gasoline increases efficiency of method with low total flow through metathesis reactor.

11 cl, 3 dwg

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims advantage and priority according to application for US patent No. 13/663,690, filed October 30, 2012, the contents of which are fully incorporated into this application by reference.

STATEMENT ON RESEARCH AND SCIENTIFIC DEVELOPMENT,

FUNDED AT THE FEDERAL LEVEL

Not applicable.

FIELD OF THE INVENTION

The invention generally relates to a method for the production of propylene. More specifically, the invention relates to methods for the production of propylene, including recycling of C ₅₊ olefins.

BACKGROUND

This section presents information from the art that may be associated with or provide context on some aspects of the methods described herein and / or stated below. This information is prerequisites for promoting a better understanding of what is disclosed in this document. What is the material used in the examination of the application. Despite the fact that such a technical field is associated with this invention, this in no way means that it also represents the prior art. A related field of technology may or may not be the prior art. The discussion should be read in this light, and not as recognition of the prior art.

Propylene can be prepared by exchanging linear butene (n-butene) with ethylene. Similar methods can lead to the production of C ₅₊ olefins, which are often used to mix gasolines (i.e. C ₅₊ olefin gasoline). At a given temperature, one way to increase the production coefficient of propylene in C ₅₊ olefin gasoline is to increase the ratio of ethylene to butene at the inlet to the reactor. However, such an increase requires increased recycling of ethylene.

The invention seeks to solve or at least reduce one or all of the above problems.

SUMMARY

Various embodiments of the invention include propylene production methods. The methods typically include an exchange reaction of a feed stream consisting of a mixture of n-butene with ethylene in the presence of a metathesis catalyst through an exchange reaction to form a fraction containing propylene, ethylene, butene and C ₅₊ olefins; isolation of propylene from ethylene, butene and C ₅₊ olefins from the metathesis product fraction; and recycling at least a portion of the C ₅₊ olefins for the metathesis reaction.

One or more embodiments includes the method described in the preceding paragraph and, in addition, include an exchange reaction of the feed stream with ethylene in the presence of a metathesis catalyst and an isomerization catalyst to form a fraction of metathesis products.

One or more embodiments includes the method described in the previous paragraph, according to the invention, ethylene is introduced into the metathesis reaction in a ratio sufficient to maintain the reaction, and the C ₄₊ ratio for reacting with the metathesis catalyst is in the range of 0.3: 1 to 3: 1.

One or more embodiments include the method described in the previous paragraph, according to the invention, at least 5% of the C ₅₊ olefins are returned to the metathesis reaction.

One or more embodiments includes the method described in the previous paragraph, according to the invention, the metathesis catalyst comprises a transition metal oxide.

One or more embodiments includes the method described in the previous paragraph, according to the invention, the metathesis catalyst comprises tungsten oxide.

One or more embodiments includes the method described in the previous paragraph, according to the invention, at least 95% of the C ₅₊ olefins are returned to the metathesis reaction.

One or more embodiments include a method for generating propylene, including: a feed stream exchange reaction consisting of a mixture of n-butene with ethylene in the presence of a metathesis catalyst through an exchange reaction to form a fraction containing C ₅₊ propylene, ethylene, butene and olefins; recovering at least a portion of propylene from the metathesis product fraction to form an upper fraction and a lower fraction with distilled propane containing C ₅₊ butene and olefins; recovering at least a portion of ethylene from the fraction of either the metathesis product or the upper fraction to form an ethylene fraction; regeneration of propylene from the upper fraction; recirculation of at least a portion of the ethylene fraction to the metathesis reaction; the allocation of at least part of butene from the bottom fraction with distilled propane to form a fraction of butene and the bottom fraction with distilled propane; recycling at least a portion of the butene fraction to the metathesis reaction; and continuous recirculation of at least a portion of the bottom fraction with distilled propane to the metathesis reaction.

One or more embodiments include the method described in the previous paragraph, and further include the exchange of the feed stream with ethylene in the presence of a metathesis catalyst and an isomerization catalyst to form a fraction of metathesis products.

One or more embodiments includes the method described in the previous paragraph, according to the invention, the isomerization catalyst contains magnesium oxide.

One or more embodiments includes the method described in the previous paragraph, according to the invention, ethylene is introduced into the metathesis reaction in a ratio sufficient to maintain the reaction, and the C ₄₊ ratio for reacting with the metathesis catalyst is in the range of 0.3: 1 to 3: 1.

One or more embodiments includes the method described in the previous paragraph, according to the invention, at least 60% of the butene fraction is recycled to the metathesis reactor.

One or more embodiments includes the method described in the previous paragraph, according to the invention, this method has an efficiency of at least 95%.

One or more embodiments includes the method described in the previous paragraph, according to the invention, the metathesis catalyst comprises a transition metal oxide.

One or more embodiments includes the method described in the previous paragraph, according to the invention, the metathesis catalyst comprises tungsten oxide.

One or more embodiments includes the method described in the previous paragraph, according to the invention, 5-90% of the bottom fraction with distilled propane is recycled to the metathesis reactor.

One or more embodiments includes the method described in the previous paragraph, according to the invention, at least 80% of the butene fraction is recycled to the metathesis reactor.

One or more embodiments includes the method described in the previous paragraph, according to the invention, at least 95% of the butene fraction is recycled to the metathesis reactor.

The above paragraphs are a simplified summary of the recently disclosed subject matter in order to provide a basic understanding of some of the aspects presented therein. The summary is not an exhaustive overview and is not intended to identify key or critical elements in order to describe the scope of the subject stated below. Its sole purpose is to present some concepts in a simplified form as an introduction to the more detailed description below.

BRIEF DESCRIPTION OF THE DRAWINGS

The claimed subject matter may be understood by reference to the following description in combination with the accompanying drawings, in which like reference numerals indicate like elements.

Fig. 1 illustrates a simplified flow diagram of a process for producing propylene.

Fig. 2 illustrates the consumption of ethylene and the production of C ₅₊ propylene and olefin gasoline in comparison with a fraction of the processed C ₅₊ olefin gasoline, using a specific example.

Fig. 3 illustrates the throughput of the reactor in comparison with the efficiency of the method in a specific example.

Although the invention is subject to various modifications and alternative forms, the drawings illustrate specific embodiments described in detail herein by way of example. It should be understood, however, that the description of specific embodiments provided herein is not intended to limit the invention to the particular forms disclosed, but rather, the invention should cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined in the attached the claims.

DETAILED DESCRIPTION

Illustrative embodiments of the subject matter below will be disclosed herein. In order to provide clarity, not all features of the actual implementation are described in this description. It should be borne in mind that when developing any such real implementation option, it is necessary to make numerous decisions on the specific implementation of the invention in order to achieve the specific goals of the developers, such as observing the restrictions associated with the system and business activity, which will vary from one implementation to another. In addition, it should be borne in mind that such development efforts, even if they are complex and time-consuming, will constitute the everyday affairs of those skilled in the art who benefit from this disclosure.

In the description below, unless otherwise indicated, all compounds described herein may be substituted or not substituted, and the list of compounds includes derivatives thereof. In addition, various ranges and / or numerical limitations may be indicated immediately below. You should be aware that, unless otherwise indicated, it is assumed that the endpoints may be interchangeable. In addition, any ranges include iterative ranges of a value falling within clearly defined ranges or limitations.

Embodiments described herein include methods for generating propylene. The methods typically include an exchange reaction of a feed stream consisting of a mixture of n-butene with ethylene in the presence of a metathesis catalyst to form a fraction containing propylene, ethylene, butene and C ₅₊ olefins; isolation of propylene from ethylene, butene and C ₅₊ olefins; and recycling at least a portion of the C ₅₊ olefins for the metathesis reaction.

In one or more specific embodiments, the exchange reaction feed stream may be formed by contacting the first feed stream, including ethylene, with a dimerization catalyst to form a dimerization fraction, including n-butene. The term "dimerization", as used herein, refers to a chemical reaction in which two identical molecular compounds interact to form a single dimer. In the present embodiments, identical molecular compounds are typically ethylenes, while a dimer is typically butene.

The dimerization catalyst may include a catalyst known in the art which, by reaction, is capable of converting ethylene to linear C ₄ olefins (e.g., n-butene). For example, dimerization catalysts may include homogeneous catalyst compounds, including nickel. Numerous nickel-containing catalysts are known that are capable of dimerizing ethylene to butene (e.g., US Patent 4,528,415, US Patent 3,513,218 and US Patent 3,452,115).

Alternatively, the dimerization catalyst may include an organoaluminum compound of the formula R _n AlX _3-n , where R is selected from alkanes such as butyl, ethyl and methyl, X is selected from halogens such as chlorine, and n = 0.1 or 2, eg.

Although dimerization can be carried out in any type of reactor, a fixed bed reactor is a specific example. Dimerization can be carried out under moderate conditions, such as, for example, temperatures from 20 ° C to 400 ° C, from 25 ° C to 150 ° C, or from 30 ° C to 55 ° C and a pressure of 200 psi. inch hut up to 400 psi inch gage, from 250 psi inch hut up to 350 psi inch hut or from 265 psi inch hut up to 315 psi inch hut

In addition, it is assumed that, depending on the nature of the source of the metathesis feed stream, the metathesis feed stream can be separated in a butane fractionation system (for example, butane distillation, described in detail below) until the metathesis is used as a feed stream.

As mentioned above, the embodiments described herein include an exchange reaction of a feed stream with ethylene in the presence of a metathesis catalyst through an exchange reaction to form a fraction of metathesis products (i.e., metathesis reaction / exchange reaction). Used in this description, the term "metathesis" refers to the equilibrium reaction between two olefins, in which the double bond of each olefin is broken to form intermediate reagents. These intermediates recombine to form new olefin products. In one or more of the specific embodiments discussed herein, two olefins include ethylene and butene, and the new olefin product is propylene.

In addition, as discussed earlier in this document, n-butene is fed into the exchange reaction via a feed stream of the exchange reaction. Ethylene can be fed into the reactor by any suitable method known to those skilled in the art. For example, ethylene can be fed into the exchange reaction through an inlet located separately from the inlet used to supply the feed stream of the exchange reaction. Alternatively, ethylene may be combined with the metathesis of the feedstream of the exchange reaction before the feedstream of the exchange reaction passes through such an inlet.

The metathesis reaction involves contacting butene with ethylene in the presence of a metathesis catalyst. Metathesis catalysts are well known in the art (see, for example, US Patent 4,513,099 and US Patent 5,120,894). Typically, the metathesis catalyst includes transition metal oxide, such as, for example, transition metal oxides of cobalt, molybdenum, rhenium, tungsten, and combinations thereof. In one or specific embodiments, the metathesis catalyst includes tungsten oxide. The metathesis catalyst may be supported on a carrier such as, for example, silica, alumina, titanium dioxide, zirconia, zeolites, clays, and mixtures thereof. In one or more embodiments, the carrier is selected from silica, alumina, and combinations thereof. The catalyst may be supported on a carrier by methods known in the art, such as, for example, adsorption, ion exchange, impregnation or sublimation. The metathesis catalyst may include, for example, 1-30% of the mass. or 5-20% of the mass. transition metal oxide.

The metathesis reaction may further include contacting butene with ethylene in the presence of an isomerization catalyst (either sequentially or simultaneously with the metathesis catalyst). The isomerization catalyst is typically adapted to convert 1-butene present in the feed stream of an exchange reaction to 2-butene in a subsequent propylene production reaction. Isomerization catalysts may include, for example, zeolites, metal oxides (e.g. magnesium oxide, tungsten oxide, calcium oxide, barium oxide, lithium oxide and combinations thereof), mixed metal oxides (e.g. silicon dioxide-alumina, zirconia- silica), acidic clays (see, for example, US Patent 5,153,165; US Patent 4,992,613; US Patent Publication 2004/0249229 and US Patent Publication 2006/0084831) and combinations thereof. In one or specific embodiments, the catalyst is magnesium oxide. Magnesium oxide may have a surface area of at least 1 m ² / g or 5 m ² / g, for example.

The isomerization catalyst may be supported on a support material. Suitable carrier materials include: silica, alumina, titanium dioxide, silica and alumina, and combinations thereof, for example.

Metathesis reactions can occur, for example, at pressures of 150 psi. inch hut up to 600 psi inch gage, from 200 psi inch hut up to 500 psi inch hut or from 240 to 450 psi. inch hut The metathesis reaction can occur, for example, at a temperature of 100-500 ° C, 200-400 ° C or 300-350 ° C. The metathesis reaction can occur, for example, at a space velocity of 3-200 h ^-1 or 6-40 h ^-1 .

The contact time required to obtain the desired yield of the products of the exchange reaction depends on several factors, such as, for example, catalyst activity, temperature and pressure. However, in one or more embodiments, the period of time during which the feed stream of the exchange reaction and ethylene is contacted with the catalyst may vary, for example, from 0.1 s to 4 hours or from 0.5 s to 0.5 hours. Metathesis reaction can be carried out periodically or continuously by using, for example, fixed catalyst beds, suspended catalyst, fluidized beds, or using any other conventional contacting techniques.

The metathesis product fraction typically contains ethylene, propylene, C ₄ olefins and C ₅₊ opheline (including, for example, pentane and hexane). Thus, the method typically involves separating the components of the metathesis product fraction. An example of the isolation method is presented in US Pat. No. 7,214,841, which is incorporated herein by reference, and such methods typically comprise isolation in a fractionation system (although it is contemplated that alternative methods such as membrane isolation can be used). As used herein, the term “fractionation” refers to methods for isolating components based on the relative volatility and / or boiling point of the components. Fractionation methods may include methods known in the art, and the term “fractionation” may be used interchangeably herein with the terms “distillation” and “fractional distillation”.

The fractionation system typically includes an ethylene distillation unit, a propane distillation unit, and a butene distillation unit. The ethylene distillation unit receives and isolates a fraction of metathesis products, including propylene, ethylene, butene and C ₅₊ olefins, to form a recycle of the ethylene fraction and the lower fraction with distilled ethylene. The recycled ethylene stream mainly consists of recovered ethylene, and at least a portion of the recycled ethylene stream can be recycled back to the exchange reaction. The lower fraction with distilled ethane usually contains propylene, butene and C ₅₊ olefins.

The propane distillation unit receives and separates products with distilled ethylene to produce propylene and a lower fraction with distilled propane. The propylene stream mainly consists of a propylene product. The bottom fraction with distilled propane usually contains C ₅₊ butene and olefins.

In one or more specific embodiments, at least a portion of the bottoms with distilled propane 130 may be recycled back to the exchange reaction. For example, 0-95%, 0-30%, 0-25% or 5% - approximately 20% of the lower fraction with distilled propane 130 (which can be assigned to the first part of the lower fraction with distilled propane) can be recycled back to the exchange reaction .

The butene stripping unit receives and extracts at least a portion of the bottom fraction with distilled propane 130 (which can be attributed to the second part of the bottom fraction with distilled propane when the first part is recycled to the exchange reaction) to form a recycle fraction of butene and the bottom fraction with distilled butene. The recycle stream of butene 128 consists predominantly of recovered butene, and the bottoms fraction with distilled butene 130 typically contains C ₅₊ olefins (interchangeably referred to herein as “C ₅₊ olefin gasoline”). In some embodiments, a purge of the upper fraction of C ₄ 129 may be used.

In one or more specific embodiments, at least a portion of the bottom fraction with distilled butene is recycled back to the exchange reaction. For example, 60-100%, at least 70%, at least 80%, at least 90%, or at least 95% of the lower fraction with distilled butene can be recycled back to the exchange reaction. Any non-recycle bottoms with distilled butene can be used as a C ₅₊ olefin gasoline product (for example, a heavier olefin stream suitable for mixing gasoline).

The molar ratio of ethylene to C ₄₊ olefins in contact with the metathesis catalyst may range from 0.1: 1 to 3: 1, from 0.3: 1 to 2: 1, or from 1: 1 to 2: 1, for example .

The embodiments described herein (for example, recycling C ₅₊ olefins back to an exchange reaction) can lead to an increase in propylene production (compared to identical methods in the absence of C ₅₊ olefin gasoline recycling) without a significant increase in ethylene consumption. In addition, the embodiments described herein are capable of providing high process efficiency (for example, at least 85%, at least 95%, or at least 98%). Used in this description, the term "process efficiency" is defined as the difference (production of propylene minus the production of olefin gasoline C ₅₊ minus the supply of ethylene) divided by the total stream of butene.

We turn now to Fig. 1, which illustrates a simplified flow diagram of a method 100 for producing propylene in accordance with embodiments disclosed herein. In fig. 1 shows a process 100 comprising introducing a feedstream of an exchange reaction 102 into a metathesis reactor 104 in which a metathesis catalyst 105 is present (and, optionally, an isomerization catalyst is not shown) to form a fraction of metathesis products 106, including propylene, ethylene, butene and olefins C ₅₊ . In fig. 1 shows a specific embodiment in which ethylene is mixed with a feed stream of an exchange reaction 102 via line 108; however, it is contemplated that ethylene may be contacted with the feed stream of an exchange reaction by methods known in the art.

A fraction of metathesis products 106 is transferred to an ethylene stripping unit 110 so as to separate at least a portion of ethylene from a fraction of metathesis products 106 to form a recycle stream of ethylene 112 and a bottom fraction with distilled ethylene 114, including C ₄₊ propylene and olefins. In the specific embodiment shown in fig. 1, a recycle stream of ethylene 112 is recycled back to the metathesis reactor 104 by methods known in the art.

The bottom fraction with distilled ethylene 114 is transferred to the propane stripping unit 116 so as to separate at least a portion of the propylene from the bottom fraction with distilled ethylene 114 and form a stream of propylene 118 and the bottom fraction with distilled propane 120, including C ₄₊ olefins. Optionally, at least a portion (eg, a first portion) of the bottom fraction with propane distilled 120 may be recycled back to the metathesis reactor 104 via line 122 by known methods. The non-recycle portion of the bottom fraction with distilled propane 120 (in some embodiments, all the bottom fractions with distilled propane 120, and in other embodiments, the second part) is transferred via line 124 to butene stripping unit 126.

The butene stripping unit 126 separates at least a portion of butene from the bottom fraction with distilled propane 124 to form a recycle stream of butene 128 and the bottom fraction with distilled butene 130, including C ₅₊ olefins. At least part of the butene recycle stream 128 and at least a portion of the bottom fraction with distilled butene 130 are recycled back to the metathesis reactor 104. Optionally, part of the butene recycle stream is withdrawn from process 100 as a purge product 132.

Those skilled in the art having the advantage of this disclosure will recognize that there are a number of suitable isolation methods known in the art that can be used to achieve such isolation. Any such suitable technique may be used.

Examples

In order to facilitate a better understanding of the invention, the following examples of embodiments are provided. In no case should the following examples be construed as limiting or defining the scope of the invention.

Based on the embodiments described herein for various ratios of ethylene or C ₅₊ recycled olefin gasoline, material balances were prepared based on the simultaneous equilibrium of the metathesis reaction and the olefin isomerization reactions. In fig. 2 shows the consumption of ethylene and the production of propylene and C ₅₊ olefin gasoline in comparison with the fraction of processed C ₅₊ olefin gasoline. Reaction conditions: 650 ° F and a molar ratio at the inlet of 1: 1 ethylene: (butenes plus pentenes), remained constant when C ₅₊ olefin gasoline recirculation rates changed _. Comparing the options for increasing ethylene recycling with processed C ₅₊ olefin gasoline _, Fig. 3, it can be seen that increasing ethylene recycling has diminishing returns, while C ₅₊ olefin gasoline recycling approaches nearly 100% butene efficiency with a lower overall flow through the metathesis reactor at high efficiency.

Conclusion of a detailed description

Thus, the invention is well suited to achieve these end results and advantages, as well as those that are inherent in it. The specific embodiments disclosed above are for illustrative purposes only, since the invention can be modified and implemented in various, but equivalent ways, obvious to those skilled in the art who are advantageous in this regard. In addition, no restrictions presented in this document are not aimed at design features or design, except for the methods described in the following claims. In this regard, it is obvious that the specific embodiments disclosed above can be changed or modified, and all such variations should be considered within the scope and essence of the invention.

The invention, illustratively disclosed herein, can be appropriately implemented in the absence of any element whose disclosure is missing here, and / or any additional element disclosed. Although the compositions and methods are described in terms of “consisting of,” “comprising” or “including” various components or steps, the compositions and methods may also “consist essentially of” or “consist of” various components and steps. All numbers and ranges described above may vary depending on some quantity. Whenever a numerical range is disclosed with a lower limit and an upper limit, any number and any included ranges falling outside the limits should be described separately. In particular, each range of values (of the form “from about a to about b,” “from about a to b,” or, equivalently, “approximately a to b”) disclosed herein should be understood as a summary of each number and the range covered by a wide range of values.

The following patents and / or patent applications incorporated herein by reference for the purposes described above should be construed as if they were set forth literally in this document:

US patent 4,528,415, entitled "Ethylene Dimerization", published July 9, 1985, on behalf of the inventor (s) Ronald D. Knudsen et al. (Ronald D. Knudsen et al.) And formalized Phillips Petroleum Co. (Phillips Petroleum Co.);

US patent 3,513,218, entitled "Dimerization of olefins", published July 19, 1970, on behalf of the inventor (s) Volkert Folkings et al. (Volkert Falkings et al.) And formally assigned to the Solven Cheral;

US patent 3,452,115, entitled "Method for the dimerization of olefins", published June 24, 1969, on behalf of the inventor (s) Wolfgang Schneider et al. (Wolfgang Schneider et al.) And formally assigned "B.F. Goodrich Co." (B.F. Goodrich Co.);

US Patent 4,513,099, entitled "Olefin Exchange Reaction and Catalysts," published April 23, 1985, on behalf of inventor (s) Simon G. Kukes et al. (Simon G. Kukes et al.) And formalized Phillips Petroleum Co. (Phillips Petroleum Co.);

US patent 5,120,894, entitled "The process of conversion of olefins", published June 9, 1992, on behalf of the inventor (s) Michael W. McCowley et al. (Michael W. McCauley et al.) And formally assigned Lyondell Petrochemical Co. (Lyondell Petrochemical Co.);

US patent 5,153,165, entitled "Preparation of Oxide Alkaline Earth Catalysts," published October 6, 1992, on behalf of inventor (s) Richard E. Lowery et al. And formally assigned Phillips Petroleum Co. (Phillips Petroleum Co.);

US patent 4,992,613, entitled "Method of double bond isomerization using basic zeolite catalysts", published February 12, 1991, on behalf of the inventor (s) Thomas F. Braunscomb et al. (Thomas F. Brownscombe et al.) And formally named Shell Oil Co. (Shell Oil Co.);

US patent 7,214,841, entitled "Processing C4 olefin streams to maximize propylene production," published May 8, 2007, on behalf of inventor (s) Robert J. Gartside et al. (Robert J. Gartside et al.) And formally assigned ABB Lummus Global Inc. (ABB Lummus Global Inc.);

U.S. Patent Publication 2004/0249229, entitled "Carboxylic Acid Isomerization of Olefins," published December 9, 2004, on behalf of inventor (s) Jeffrey C. Gee et al. (Jeffery C. Gee et al.) And formalized Chevron Phillips Chemical Co. (Chevron Phillips Chemical Co.);

US Patent Publication 2006/0084831 entitled "Method for Isomerizing Alpha Olefins into Internal Olefins," published April 20, 2006, on behalf of inventor (s) Jian Jian Zhang and formally assigned to Hercules Inc. (Hercules Inc.).

In the event that any incorporated patent, patent application, or other reference materials are contrary to this disclosure, this disclosure shall prevail.

This concludes the detailed description. The specific embodiments disclosed above are for illustrative purposes only, since the invention can be modified and implemented in various, but equivalent ways, obvious to those skilled in the art who are advantageous in this regard. In addition, no restrictions presented in this document are not aimed at design features or design, except for the methods described in the following claims. In this regard, it is obvious that the specific embodiments disclosed above can be changed or modified, and all such variations should be considered within the scope and essence of the invention. Accordingly, the protective actions that we sought in this document should be performed as described below in the claims.

Claims (23)

1. The method of production of propylene, includes: a metathesis reaction of a feed stream consisting of a mixture of n-butene with ethylene in the presence of a metathesis catalyst to form a fraction containing propylene, ethylene, butene and C ₅₊ , 2-pentene and 3-hexene olefins; isolation of propylene from ethylene, butene and C ₅₊ olefins from the metathesis product fraction; and recirculation of at least a portion of the C ₅₊ olefins for the metathesis reaction, wherein the recirculated C ₅₊ olefins are converted to propylene and butenes, the ethylene being introduced into the metathesis reaction in a ratio sufficient to maintain the reaction, where the C ₄₊ ratio for reaction with a metathesis catalyst is in the range of 0.3: 1 to 3: 1, and at least 5% of the C ₅₊ olefins are returned to the metathesis reaction. 2. The method according to p. 1, further comprising a reaction of exchanging the feed stream with ethylene in the presence of a metathesis catalyst and an isomerization catalyst to form a fraction of metathesis products. 3. The method according to p. 1, characterized in that the metathesis catalyst contains a transition metal oxide, preferably tungsten oxide. 4. The method according to p. 1, characterized in that at least 95% of the C ₅₊ olefins are returned to the metathesis reaction. 5. The method of production of propylene includes: an exchange reaction of a feed stream consisting of a mixture of n-butene with ethylene in the presence of a metathesis catalyst to form a fraction containing propylene, ethylene, butene and C ₅₊ olefins; recovering at least a portion of propylene from the metathesis product fraction to form an upper fraction and a lower fraction with distilled propylene containing butene and C ₅₊ olefins; recovering at least a portion of ethylene from a fraction or a metathesis product or upper fraction to form an ethylene fraction; extraction of propylene from the upper fraction; recirculation of at least a portion of the ethylene fraction to the metathesis reaction; recovering at least a portion of butene from the bottom fraction with distilled propylene to form a fraction of butene and a bottom fraction with distilled propylene; recycling at least a portion of the butene fraction to the metathesis reaction; and continuous recirculation of at least part of the lower fraction with distilled butene or part of the lower fraction with distilled propylene in a metathesis reaction, moreover, the recycled C ₅₊ olefins are converted to propylene and butenes, and ethylene is introduced into the metathesis reaction in a ratio sufficient to maintain the reaction, where the C ₄₊ ratio for reacting with the metathesis catalyst is in the range from 0.3: 1 to 3: 1 and at least 5% of C ₅₊ olefins are returned to the metathesis reaction. 6. The method according to p. 5, further comprising a reaction of exchanging the feed stream with ethylene in the presence of a metathesis catalyst and an isomerization catalyst to form a fraction of metathesis products. 7. The method according to p. 6, characterized in that the isomerization catalyst contains magnesium oxide. 8. The method according to p. 5, characterized in that at least 60% of the butene fraction is recycled to the metathesis reactor, preferably (a) at least 80% of the butene fraction is recycled to the metathesis reactor or (b), at least 95% of the butene fraction was recycled to the metathesis reactor. 9. The method according to p. 5, having an efficiency of at least 95%. 10. The method according to p. 5, characterized in that the metathesis catalyst contains a transition metal oxide, preferably tungsten oxide. 11. The method according to p. 5, characterized in that 5-90% of the lower fraction with distilled propylene is recycled to the metathesis reactor.

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